Disposable pull-on diaper

ABSTRACT

Disposable pull-on diapers of the present disclosure may have optimized waist circumferential length and leg opening length.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/417,805, filed on Jan. 27, 2017, which is a continuation of U.S.patent application Ser. No. 15/007,504, filed on Jan. 27, 2016, now U.S.Pat. No. 9,592,163, issued on Mar. 14, 2017, which is a continuation ofU.S. patent application Ser. No. 13/494,069, filed on Jun. 12, 2012, nowU.S. Pat. No. 9,278,032, issued on Mar. 8, 2016, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/564,873,filed on Nov. 30, 2011, the entire disclosures of which are fullyincorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure relates to disposable pull-on diapers which canbe donned by inserting the wearer's legs into the leg openings andsliding the diaper up into position about the lower torso.

BACKGROUND OF THE INVENTION

Disposable pull-on diapers have been well known and successfullycommercialized. For example, WO 2006/017718 describes a disposablepull-on diaper having a waist opening and two leg openings. Thedisposable pull-on diaper comprises an absorbent main body and aring-like elastic belt. The absorbent main body comprises a liquidpervious topsheet, a liquid impervious backsheet, and an absorbent coredisposed therebetween. The ring-like elastic belt comprises a beltsubstrate layer and a belt elastic material joined to the belt substratelayer. The two longitudinal ends of the absorbent body are joined to thering-like elastic belt in front and back.

Tape-type and pull-on type diapers are the two main types of disposablediapers. Pull-on diapers are recently increasing popularity due to theconvenience of applying a pull-on diapers on an infant. When putting atape-type diaper on an infant, to achieve comfortable fit, a care-takerneeds to pay close attention to the positioning of the diaper relativeto the infant's body and the stretching level applied in taping diaper'sears to its landing zone. In contrast, pull-on diapers have predefinedwaist opening and leg openings and thus allows a care-taker to put thediapers on an infant's body by simply inserting the infant's legs in theleg opening and pulling the diaper up over the waist. So far, pull-ondiapers have mainly been successful in large and medium sized diapers.However, there is much area for improvement for pull-on diapers in smallsize.

Small-sized diapers are intended for use on infants having body weightof less than 8 kilograms. Infants of this body size are typically lessthan 10 months old and in average, they sleep about 13-18 hours a day.For them, diapers are more likely changed while they are sleeping.Hence, it is desirable that the small-sized diapers can be applied ontothe infants with ease so that their sleep will not be disturbed.Furthermore, small-sized infants typically have thighs of greatercircumference but smaller waist than medium and large sized infants. Inaddition, the legs of small-sized infants are usually not in astraightened state, but are more often in a curved position whichrequires a wider waist opening to put the diaper through the curvedlegs. Hence, to simply downsize medium and large sized pull-on diapersto small size would not provide desirable waist and leg fit as well asthe desirable ease of application.

Also, it has been found that currently commercialized small-sizedpull-on diapers are not stretchable enough to be applied with ease. Somehave also been found not to fit well in legs. Therefore, there is stilla need for a small-sized disposable pull-on diaper which can be appliedwith ease and can fit the waist and legs of a wearer better.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which is regarded as formingthe present disclosure, it is believed that the invention will be betterunderstood from the following description which is taken in conjunctionwith the accompanying drawings and which like designations are used todesignate substantially identical elements, and in which:

FIG. 1 is a perspective view of a preferred embodiment of the disposablepull-on diaper of the present disclosure in an in-use configuration;

FIG. 2 is a top plan view of a preferred embodiment of the pull-ondiaper in its flat free-state condition with the front belt portion andback belt portion separated and showing the inner surface of the diaper;

FIG. 3 is a cross-sectional view of FIG. 2 taken along the line III-III;

FIG. 4 is a cross-sectional view of FIG. 2 taken along the line IV-IV;

FIG. 5 is a schematic plan view of a preferred embodiment of the diaperof the present disclosure in its flat free-state condition showing theouter surface of the diaper;

FIG. 6(a) is a schematic front view of a disposable pull-on diaper in afree-state;

FIG. 6(b) is a schematic front view of a disposable pull-on diaper in astretched state;

FIG. 6(c) is a schematic right side view showing one of the leg openingsof the diaper in shadow;

FIG. 7 is a schematic view showing the process for forming the pull-ondiaper shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term “pull-on diaper” refers to diapers which have adefined waist opening and a pair of leg openings and which can be pulledonto the body of wearers by inserting their legs into the leg openingsand pulling the article up over their waists. The term “small sizeddiaper”, also known as “S size” diaper refers to diapers for infantshaving a body weight of less than 8 kilograms. Medium sized diaper”,also known as “M size” diapers refers to diapers for infants having abody weight of from about 7 kilograms to about 10 kilograms. “Largesized diaper”, also known as “L size” diapers refers to diapers forinfants having a body weight of from about 9 kilograms to about 14kilograms.

A preferred embodiment of the small sized disposable pull-on diaper 20of the present disclosure is shown in FIG. 1. FIG. 1 is a perspectiveview of the pull-on diaper 20 of the present disclosure in an in-useconfiguration. FIG. 2 is a top plan view of the pull-on diaper shown inFIG. 1 in its flat free-state configuration with the front belt portionand back belt portion separated and with the inner surface of the diapershown. The pull-on diaper 20 has an outer surface 22, an inner surface24 opposed to the outer surface 22. The pull-on diaper 20 has alongitudinal centerline L1 and a transverse centerline T1. The diaper 20comprises an absorbent main body 38 (hereinafter may be simply referredto as “main body”) to cover the crotch region of the wearer, and aring-like elastic belt 40 (hereinafter may be simply referred to as“elastic belt”).

The Absorbent Main Body

The absorbent main body 38 absorbs and contains body exudates in use. Inthe embodiment shown in FIGS. 1 and 2, the main body 38 has a generallyrectangular shape having a longitudinal centerline L2, a transversecenterline T2, left and right longitudinally extending side edges 48(hereinafter may be referred to as “longitudinal side edge” or “sideedge”) and front and back transversely extending end edges 50(hereinafter may be referred to as “transverse end edge” or “end edge”).The main body 38 has a front waist panel 52, a back waist panel 54 and acrotch panel 56 between the front and back waist panels 52, 54. As usedherein, “front” refers to the direction that a wearer is facing when thediaper is worn and “back” refers to the direction of a wearer's backwhen the diaper is worn. The main body may have shapes other thanrectangle, such as an hour-glass shape with the crotch panel 56 has aninwardly curved side edges.

Referring to FIG. 3, the main body 38 comprises a liquid pervioustopsheet 58, a liquid impervious backsheet 60 and an absorbent core 62disposed there between. At least one leg elastic material 118 isdisposed in proximity to each of the longitudinal side edges 48 andextends generally along the longitudinal side edges. The main body 38may additionally comprise a barrier leg cuff 64 disposed along thelongitudinal side edges 48. The barrier leg cuff 64 provides improvedcontainment of liquids and other body exudates in the main body. Thematerials for making barrier leg cuff and the structure of barrier legcuff are well known in the art, for example, as described in WO2006/017718.

The liquid pervious topsheet 58 is optionally positioned adjacent to thebody-facing surface of the absorbent core 62 and may be joined theretoand/or to the backsheet 60 by any attachment means known in the art. Theliquid impervious backsheet 60 is generally that portion of the diaper20 positioned adjacent to the garment-facing surface of the absorbentcore 62 and prevents exudates absorbed and contained therein fromsoiling articles that may contact the diaper 20. The absorbent core ispositioned between the topsheet 58 and the backsheet 60 and absorbs andretains body exudates. The topsheet 58, the backsheet 60 and theabsorbent core may be manufactured from any known materials. Suitabletopsheet materials may include porous foams; reticulated foams;apertured plastic films; or woven or nonwoven webs of natural fibers(e.g., wood or cotton fibers), synthetic fibers (e.g., polyester orpolypropylene fibers), or a combination of natural and synthetic fibers.Suitable backsheet materials may include breathable materials thatpermit vapors to escape from the diaper while still preventing exudatesfrom passing through the backsheet. Suitable absorbent core materialsmay include creped cellulose wadding; meltblown polymers, includingcoform; chemically stiffened, modified or cross-linked cellulosicfibers; tissue, including tissue wraps and tissue laminates; absorbentfoams; absorbent sponges; superabsorbent polymers; absorbent gellingmaterials; or any other known absorbent material or combinations ofmaterials.

An outer cover layer 42 can be disposed on the outer surface 22 of thediaper 20 and covers at least the crotch panel 56 of the absorbent mainbody 38. The outer cover layer 42 may extend into and cover the frontand back waist panels 52, 54 of the main body 38. The outer cover layer42 is directly joined to and covers the liquid impervious backsheet 60of the main body 38. Referring back to FIG. 2, the central panel 80 ofthe front and back belt portions 84, 86 (explained herein below) isjoined to the front and back waist panels 52, 54 of the main body 38through the outer cover layer 42. Thus, the outer cover layer 42 issandwiched between the front and back belt portions 84, 86 and theliquid impervious backsheet 60 of the main body 38. The outer coverlayer 42 may comprise any known materials and may comprise materials asused for the front and back belt portions 84, 86 as explained above.Optionally the outer cover layer 42 comprises a single layer of nonwovenweb of synthetic fibers. More optionally, the outer cover layer 42comprises a single layer of hydrophobic, non-stretchable nonwovenmaterial.

The topsheet, absorbent core, backsheet and outer cover may be laterallyand/or longitudinally coextensive. However, in a preferred embodiment,the absorbent core has a narrower lateral width than that of thetopsheet and backsheet, and the topsheet has a narrower lateral widththan that of the backsheet. In the embodiment shown in FIGS. 2 and 3,the outer cover layer 42 is coextensive with the liquid imperviousbacksheet 60 which have a bigger lateral width than the topsheet 58 andabsorbent core 62. Where the topsheet, backsheet, absorbent core andouter cover have different lateral width or longitudinal length, thelongitudinal side edges 48 and transverse end edges 50 of the absorbentbody refer to the edges of the member which laterally and/orlongitudinally extends the most.

At least one leg elastic material 118 is disposed in proximity to theside edges 48 and generally extends longitudinally along the side edgesof the absorbent body 38. The leg elastic material can be in the form ofelastic strand or ribbon attached to the backsheet in an extended state.As used herein, the terms “strand” and “ribbon” refer to material inlong and thin configuration and these two terms can be usedinterchangeably. In the embodiment shown in FIG. 3, the leg elasticmaterial 118 is disposed between the outer cover layer 42 and backsheet60. The leg elastic material 118 may be disposed at least in the crotchpanel 56 of the absorbent body 38 or may be disposed along the entiretyof the longitudinal side edge 48.

Ring-Like Elastic Belt

Referring to FIGS. 1 and 2, the ring-like elastic belt 40 comprises afront belt portion 84 and a back belt portion 86 (hereinafter may bereferred to as “front and back belt portions 84, 86). Each of the frontbelt portion 84 and the back belt portion 86 has central panels 80F, 80Band side panels 82F, 82B contiguous with the central panels 80F, 80B andpositioned transversely outward from the central panels 80F, 80B.Herein, a front member and a back member may be indicated by a referencenumber with “F” suffix and “B” suffix, respectively, as necessary.Therefore, the “central panels 80F, 80B” for example indicates the“front central panel 80F” and the “back central panel 80B”. The “centralpanel 80” also may mean the “front central panel 80F” and the “backcentral panel 80B”. Each of the front and back belt portions 84, 86 hasa transversely extending distal edge 88F, 88B, a transversely extendingproximal edge 90F, 90B, and a longitudinally extending left and rightside edge 89F, 89B, respectively. Herein, the term “proximal” is used toindicate the position that is relatively closer to the crotch panel ofthe main body. Therefore, the proximal edge 90F, 90B is located closerthan the distal edge 88F, 88B relative to the crotch panel 56 of themain body 38. The central panels may partly or entirely overlap with thefront and back waist panels 52, 54 of the main body 38 respectively.However, the central panels 80F, 80B does not extend into the crotchpanel 56 of the main body 38 and is not disposed in the crotch panel 56.In the embodiment shown in FIG. 2, the central panels 80F, 80B partlyoverlaps with and is joined to the front and back waist panels 52, 54 ofabsorbent body, respectively. The front and back belt portions 84, 86are joined at or adjacent to the side edges 89F, 89B by side seams 32 toform the ring-like elastic belt. The distal edges 88F and 88B define awaist opening 36. The proximal edges 90F, 90B of side panels 82F 82Btogether with the longitudinal side edges of the crotch panel 56 ofabsorbent body 38 define two leg openings 34.

The ring-like elastic belt 40 comprises a belt substrate layer 92 (shownin FIGS. 4 and 7) and a plurality of waist elastic strands 98 and aplurality of side panel elastic strands 100 (hereinafter may becollectively referred to as belt elastic strands 96). Optionally, thering-like elastic belt further comprises an inner layer 94 so that thebelt elastic strands 96 are interposed between the two layers 92 and 94.The front and back belt portions 84, 86 may comprise the same materialand/or may have the same structure. Alternatively, the front and backbelt portions 84, 86 may comprise different materials and/or may havedifferent structures. In the embodiment of FIG. 2, the front and backbelt portions 84, 86 generally have the same layer structure. The beltsubstrate layer 92 and inner layer 94 can be manufactured from a widerange of materials such as plastic films; apertured plastic films; wovenor nonwoven webs of natural materials (e.g., wood or cotton fibers),synthetic fibers (e.g., polyolefins, polyamides, polyester,polyethylene, or polypropylene fibers), or a combination of naturaland/or synthetic fibers; or coated woven or nonwoven webs. Optionally,the belt substrate layer 92 and inner layer 94 comprise a nonwoven webof synthetic fibers. More optionally, the belt substrate layer 92 andinner layer 94 comprise hydrophobic, non-stretchable nonwoven material.

The plurality of waist elastic strands 98 are attached to the beltsubstrate layer 92 in proximity to the distal edge 88 and the side panelelastic strands 100 are attached to the belt substrate layer at least inboth left and right side panels 82. The waist elastic strands 98 andside panel elastic strands 100 comprise one or more of elastic strandsextending in the transverse direction. The plurality of waist elasticstrands 98 and the plurality of side panel elastic strands 100 areattached to the belt substrate layer 92 or interposed between the beltsubstrate layer 92 and the inner layer 94 by adhesives under stretchedcondition such that the front and back belt portions 84, 86 provideselasticity when the diaper 20 is used.

In the embodiment shown in FIG. 2, waist elastic strands 98 and sidepanel elastic strands 100 are disposed at a constant interval in thelongitudinal direction. Alternatively, the waist elastic strands 98 andthe side panel elastic strands 100 may be disposed at a differentinterval in the longitudinal direction. The different longitudinalintervals can provide an improved fit to a wearer's body anatomy. Forexample, waist elastic strands can be disposed at a smaller longitudinalinterval than that of side panel elastic strands. The waist elasticstrands 98 can run continuously from the left longitudinal side edge tothe right longitudinal side edge of the belt substrate layer and canform an elastic ring when the front and back belt portions 84, 86 arejoined together. No elasticity may be provided in a portion of thecentral panel 80 of the front and back belt portions 84, 86 whichoverlaps with the front and back waist panels 52, 54 of the main body38. This can be achieved by providing no elastic material in the centralpanel or deactivating any elastic materials present in the centralpanel. However, an elastic material may be provided in the central panel80 if it is necessary.

As shown in FIG. 5, the front side panel 82F has a longitudinal lengthLF defined by the front side edge 89F of the front belt portion 84 andthe back side panel 82B has a longitudinal length LB defined by the backside edge 89B of the back belt portion 86. In a preferred embodiment,the front belt portion 84 and the back belt portion 86 can be formedsuch that the longitudinal lengths LB of the back side panels 82B of theback belt portion 86 are greater than the longitudinal lengths LF of thefront side panels 82F of the front belt portion 84. The front and backbelt portions 84, 86 are formed by cutting a belt layer web along a cutline. The forming process will be described in detail hereinbelow. Whenthe diaper is assembled to form the waist opening 36 and the legopenings 34, the diaper 20 is folded along the transverse centerline T1such that the front distal edge 88F is aligned with the back distal edge88B. The front side edge 89F is also aligned with a portion of the backside edge 89B. Then the front and back belt portions 84, 86 are joinedat or adjacent to the front and back side edges 89F, 89B by the sideseams 32. The front and back proximal edges 90F, 90B, however, are notaligned to one another. The back proximal edge 90B is disposedlongitudinally closer than the front proximal edge 90F relative to thetraverse centerline T1 such that the proximal portion 93B of the backside panel 82B extends toward the crotch panel 56 of the main body 38beyond the front proximal edge 90F. The side edge of the proximalportion 93B is not joined to anywhere and is free from attachment. Theratio of the longitudinal length LB of the back side edge 89B to thelongitudinal length LF of the front side edge 89F is optionally betweenabout 1.1 and about 2.0, more optionally between about 1.2 and about 1.5in a laid out flat configuration of the diaper. The diaper having thesedimension characteristics provides an effective buttock cover withouthindering the wearer from inserting legs into the leg opening.

Dimension of the Small-Sized Disposable Pull-on Diaper

The small-sized disposable pull-on diaper of the present disclosure hasan optimized dimension and provides desirable ease of application andwaist and leg fit properties.

FIG. 6(a) is a schematic front view of a small-sized disposable pull-ondiaper of the present disclosure in free state. FIG. 6(b) is a schematicfront view of a small-sized disposable pull-on diaper of the presentdisclosure in stretched state. FIG. 6(c) is a schematic right side viewof the small-sized disposable pull-on diaper in free state showing oneof the leg openings in shadow. As used herein, “free state” refers to astate that the elastic material in the diaper is allowed to contractunder an unused condition, and the diaper is free from any stretchingforce. As used herein, “stretched state” refers to a state that thering-like elastic belt of the diaper is stretched to its maximumdimension which is substantially same to the dimension of the beltsubstrate layer with elastic strands being removed.

As shown in FIGS. 6(a) and 6(b), the diaper has a free-state waistcircumferential length which is 2Tf, and a stretched waistcircumferential length which is 2Tx. Tf indicates the dimension of thefirst waist elastic strand 98 a from the distal edge 88 of the beltsubstrate layer 92 between the inner edge of the left and right sideseams 32. The side seam may have a certain width, as shown in FIG. 1.For purposes of obtaining the free-state waist circumferential lengthand the stretched waist circumferential length, the inner, wearer facingside of the diaper is measured, excluding the width of the side seam. Tfis measured by carefully attaching a flexible tape measure ribbon alongthe first waist elastic strand 98 a about every 10 mm to make sure thatthe tape measure ribbon follows the elastic strand, and then read thelength in mm. Tx is the length of the same position as for measuring Tfwhere the ring-like elastic belt is stretched to its maximum length. Txis substantially same to the length of the belt substrate layer 92 withthe waist elastic strands 98 and side panel elastic strands 100 beingremoved away from the elastic belt. Tx can be measured by tearing adiaper down, such as by using a cold spray to facilitate thedeactivation of adhesives attaching the elastic strands to the beltsubstrate layer. After the plurality of elastic strands 96 being removedand the substrate layer 92 being flattened, the length Tx is measured bya metal scale in mm.

As shown in FIG. 6(c), Sf indicates front side panel elastic length.Particularly, Sf is the length of the first side panel elastic strand100 f from the proximal edge 90F of the front side panel 82F in freestate between the inner edge of the right side seam 32 and the crosspoint of the side panel elastic strand 100 f and the first leg elasticstrand material 118 e from the side edge 48. Sb indicates back sidepanel elastic length. Particularly, Sb is the length of the first sidepanel elastic strand 100 b from the proximal edge 90B of the back sidepanel 82B in free state between the inner edge of the right side seam 32and the cross point of the side panel elastic strand 100 b and the firstleg elastic strand 118 e from the side edge 48. Le indicates leg elasticlength. Particularly, Le is the length of the leg elastic strand 118 eclosest to the side edge 48 in free state between the cross point of 118e with the front proximal edge 90F in front side panel 82F and the crosspoint of 118 e with the back proximal edge 90B in back side panel 82B.Le can be measured by using the same method as described above withrespect to the measurement of Tf. La indicates the difference in thelongitudinal length of the front belt portion LF and back belt portionLB. Leg opening length can be calculated by the following formula:

Leg opening length=Le+Sf+√{square root over (Sb ² +La ²)}

where the front belt portion and back belt portion have the samelongitudinal length, La will be zero, then the calculation of Legopening length can be simplified as:

Leg opening length=Le+Sf+Sb.

The small-sized disposable pull-on diapers of the present disclosure hasa stretched waist circumferential length from about 620 mm to about 700mm, optionally from about 640 mm to about 680 mm, and the ratio of thestretched waist circumferential length to the free-state waistcircumferential length is from about 2.5 to about 2.8, optionally fromabout 2.6 to about 2.7. In addition, the small-sized disposable pull-ondiapers of the present disclosure has a leg opening length from about250 mm to about 300 mm, optionally from about 265 mm to about 285 mm.Inventors of the present disclosure have found that small-sized pull-ondiapers having the aforementioned dimensions provide the desirable easeof application as well as waist and leg fit. Without intending to bebound by theory, it is believed that the dimension of stretched waistcircumferential length and the ratio of stretched waist circumferentiallength to free-state waist circumferential length as defined in thepresent disclosure provides a stretched waist opening which is wideenough to allow a caretaker to pull the diaper through an infant's legswith ease, meanwhile, the waist opening in free-state of the diaper willnot be too big to cause sagging in use. Similarly, the dimension of legopening length as defined in the present disclosure provides thedesirable leg fit to a wearer. Leg opening length out of the range ofthe present disclosure may increase the incidence of leakage and gathermark.

In a preferred embodiment, leg elastic length Le presents from about 50%to about 75%, optionally, from about 68% to about 72% of the leg openinglength. It has been found that the preferred percentage of leg elasticlength Le in leg opening length provides a reduced incidence of leakage.

FIG. 7 is a schematic view to explain the process for forming the diaper20. The front and back belt portions 84, 86 are formed by cutting thebelt layer web along a cut line 310. The process 300 shown in FIG. 7primarily comprises three sections; a main body forming section 302, abelt forming section 304 and an assembly section 308. Since FIG. 7 is aschematic view, it should be noted that various parts of the diaper havebeen omitted, such as the belt and leg elastic material.

The main body forming section 302 combines elements forming the mainbody 38 such as the topsheet 58, the backsheet 60, the absorbent core 62and the barrier leg cuff 64. The absorbent core 62 is sandwiched betweenthe topsheet 58 and the absorbent core 62. The outer cover layer 42 (notshown in FIG. 7) is joined to the backsheet 60 (not shown in FIG. 7) andthe leg elastic material 118 (not shown in FIG. 7) is sandwiched betweenthe backsheet 60 and the outer cover layer 42. These elements are joinedto each other by any known means such as adhesives or heat bonding toform an intermediate assembly 312. The intermediate assembly 312 is thencut into the individual intermediate assembly 312. The individualintermediate assembly 312 is turned by 90 degrees and fed into theassembly section 308.

The belt forming section 304 combines the belt substrate layer web 92and the inner layer web 94 to form a continuous belt layer web 91. Thecontinuous belt layer web 91 is cut along a straight cut line 310 whichcorresponds to the proximal edges 90F, 90B to form a continuous frontbelt web 84 and a continuous back belt web 86. The cut line 310 can bebiased from the longitudinal centerline L3 of the continuous belt layerweb 91 to differentiate the length LCF of the continuous front belt web84 and the length LCB of the continuous back belt web 86 in the crossmachine direction. The cross machine direction means the directioncrossing the machine direction at a right angle. The machine directionmeans the direction where the component material is conveyed in themanufacturing process, which is in parallel to the longitudinalcenterline L3. The belt elastic material 96 (not shown in FIG. 7) isalso attached between the inner layer web 94 and the belt substratelayer web 92. Then the continuous front belt web 84 and the continuousback belt web 86 are separated from one another along the cur line 310.

The assembly section 308 combines the individual intermediate assembly312 with the continuous front belt web 84 and the continuous back beltweb 86. The individual intermediate assembly 312 is placed on thecontinuous front and back belt webs 84, 86 at a predetermined intervalwhich become the side panel between each of the individual intermediateassemblies 312. The end flap 112 of the front and back belt webs 84, 86is folded inwardly along the distal edge 88 to form a continuous diaperassembly 314 comprising the main body 38, the outer cover layer 42 (notshown in FIG. 7) and the front and back belt webs 84, 86. The continuousdiaper assembly 314 thus formed is cut into each individual diaper 20.The individual diaper 20 has the longitudinal length LB of the back sideedge 89B being greater than the longitudinal length LF of the front sideedge 89F. The individual diaper 20 is then folded along the transversecenterline T1 in the crotch region and the front and back belt 84, 86 isjoined at the side seams 32 adjacent to the side edges 89F, 89B to formthe waist opening and the leg openings. Alternative methods for makingthe small-sized diapers of the present disclosure can be formed by aknown process in the art, such as the process described in WO2006/017718, the full disclosure of which is incorporated here byreference.

Examples

A small sized disposable pull-on diaper of the present disclosure ismade according to a method described above and named as Example.Small-sized disposable pull-on diapers having similar structure to thatof the present disclosure except dimensions as specified below are namedas Comparative Example 1 and Comparative Example 2. Dimensions of thediapers of Example and Comparative Example 1 and 2 are shown in thefollowing Table 1:

TABLE 1 Comparative Comparative Example Ex 1 Ex 2 Stretched waistcircumferential 668.5 603.2 574.4 length (2Tx) (mm) Free-state waistcircumferential 249.5 249.6 281.6 length (2Tf) (mm) Ratio of Tx/Tf 2.682.42 2.04 Leg opening length (mm) 276.2 291.2 267.3 Percentage of legelastic length 69% 77% 60% (Le) in Leg opening length

The performance with respect to ease of application and waist and legfit of the diapers of the above Example 1 and Comparative Example 1 andComparative Example 2 are assessed as described below.

Ease of Application

6 panelists are asked to apply the test diapers to a standardsmall-sized baby mannequin in turn. Each panelist is asked to apply eachof the diaper samples to the baby mannequin in turn and then rate theperformance of ease of application of each tested sample in 5 scalesfrom Very Poor to Excellent, wherein 5 represents Excellent, 4represents Good, 3 represent Fair, 2 represent Poor and 1 representsVery Poor. The mannequin is a standard S-size full mannequin with legsin a curved position. The waist circumference and thigh circumference ofthe mannequin is 407 mm and 235 mm, respectively. The test result isshown in the following Table 2:

TABLE 2 Ease of Application Test Result Comparative Comparative ExampleEx 1 Ex 2 Panelist No. a b c 1 5 3 2 2 5 4 3 3 5 4 3 4 5 3 4 5 5 4 3 6 55 3 Average 5.0bc* 3.8 3.0 *Statistically significant over ComparativeExamples 1 and 2 with 90% confidence level

Overall Fit Assessment

Panelists who have babies having body weight of 4-8 kg are asked to useeach test product for 5 days in turn. Panelists are asked to record theleakage, gather mark and sagging incidence observed when changingdiapers each time. The incidence percentage is summarized in thefollowing Table 3:

TABLE 3 Comparative Example Ex 1 a b Number of diapers used in total280   280 Urine leakage % 0b* 2.1 Gather mark % 4b* 10 Sagging % 27b* 39 *Statistically significant over Comparative Example 1 with 90%confidence level

The Example diaper of the present disclosure has significant betterperformance in ease of application. While it may be intuitively expectedthat a diaper having ease of application may also have higher leakageand sagging occurrence, the Example diaper surprisingly providessignificantly better urine leakage prevention and sagging prevention aswell as reduced incidence of gather mark. It is believed that thedefined dimensions of the present disclosure provide such unexpectedbenefit of improvement in ease of application, leakage prevention,gather mark and sagging prevention, at the same time.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present disclosure have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A disposable pull-on diaper comprising: anabsorbent main body comprising a liquid pervious topsheet, a liquidimpervious backsheet, and an absorbent core disposed therebetween,wherein the absorbent main body has left and right longitudinallyextending side edges, front and back transversely extending end edges,longitudinally opposing front and back waist panels, and a crotch panelbetween the waist panels, at least one leg elastic material disposed inproximity to each of said side edges and extending generallylongitudinally along said side edges; an elastic belt comprising a frontbelt portion and a back belt portion joined to each other at side seams,each of said front belt portion and back belt portion has transverselyextending proximal and distal edges, the distal edge of the elastic beltdefines a waist opening, the proximal edge being located closer than thedistal edge relative to the crotch panel of the absorbent main body,each of said front belt portion and back belt portion has a centralpanel; wherein the elastic belt comprises a belt substrate layer and aplurality of waist elastic strands and a plurality of side panel elasticstrands each extending in the transverse direction and attached to thebelt substrate layer; wherein said waist elastic strands are disposed inproximity to the distal edge and said side panel elastic strands aredisposed at least in the left and right side panels, and wherein theelastic belt has a stretched waist circumferential length and afree-state waist circumferential length; wherein, the central panel ofthe front belt portion is joined to the front waist panel of theabsorbent main body, the central panel of the back belt portion isjoined to the back waist panel of the absorbent main body, and theproximal edge of the respective left and right side panels of the frontbelt portion and the back belt portion together with the left and rightside edges of the crotch panel of the absorbent main body defines twoleg openings, each of the leg opening has a leg opening length which canbe calculated according to the following formula:leg opening length=Le+Sf+√{square root over (Sb ² +La ²)} wherein Leindicates leg elastic length, Sf indicates front side panel elasticlength, Sb indicates back side panel elastic length and La indicates thedifference in the longitudinal length of the front belt portion and backbelt portion; wherein, along a longitudinal axis of the disposablepull-on article, a longitudinal length of the front belt (LF) is lessthan a longitudinal length of the back belt (LB).
 2. The diaper of claim1, wherein said leg elastic length is from about 50% to 75% of the legopening length.
 3. The diaper of claim 1, wherein the leg opening lengthis from about 250 mm to about 280 mm.
 4. The diaper of claim 1, whereinthe leg opening length is from about 270 mm to about 280 mm.
 5. Thediaper of claim 4, wherein the ratio of the longitudinal length of eachof the side panels of the back belt portion to the longitudinal lengthof the side panel of the front belt portion is between about 1.1 andabout 2.0.
 6. The diaper of claim 1, wherein the ratio of the stretchedwaist circumferential length to the free-state waist circumferentiallength is from about 2.5 to about 2.8.
 7. The diaper of claim 1, whereinthe plurality of side panel elastic strands are disposed only in theleft and right side panels of the front and back belt portion.
 8. Thediaper of claim 1, wherein the waist elastic strands and side panelelastic strands are disposed at a different interval in the longitudinaldirection.
 9. The diaper of claim 1, wherein the front belt portion isfolded over to overlap a wearer-facing surface of the absorbent mainbody.
 10. The diaper of claim 1, wherein the back belt portion is foldedover to overlap a wearer-facing surface of the absorbent main body. 11.The diaper of claim 1, wherein the front belt is folded over to overlapa wearer-facing surface of the absorbent assembly.
 12. The diaper ofclaim 1, wherein the stretched waist circumferential length is fromabout 620 mm to about 700 mm.
 13. The diaper of claim 1, wherein thestretched waist circumferential length is from about 640 mm to about 680mm.
 14. The diaper of claim 1, wherein the leg opening length of thediaper includes a leg elastic length which is from about 68% to about72% of the leg opening length.
 15. The diaper of claim 1, wherein theleg opening length is from about 265 mm to 285 mm.
 16. A disposablepull-on diaper comprising: an absorbent main body comprising a liquidpervious topsheet, a liquid impervious backsheet, and an absorbent coredisposed therebetween, wherein the absorbent main body has left andright longitudinally extending side edges, front and back transverselyextending end edges, longitudinally opposing front and back waistpanels, and a crotch panel between the waist panels, at least one legelastic material disposed in proximity to each of said side edges andextending generally longitudinally along said side edges; an elasticbelt comprising a front belt portion and a back belt portion joined toeach other at side seams, each of said front belt portion and back beltportion has transversely extending proximal and distal edges, the distaledge of the elastic belt defines a waist opening, the proximal edgebeing located closer than the distal edge relative to the crotch panelof the absorbent main body, each of said front belt portion and backbelt portion has a central panel, and left and right side panelscontiguous with its central panel; wherein, the elastic belt comprises abelt substrate layer and an apertured film and attached to the beltsubstrate layer; wherein the apertured film is disposed in proximity tothe distal edge and said side panel elastic strands are disposed atleast in the left and right side panels, and wherein the elastic belthas a stretched waist circumferential length and a free-state waistcircumferential length; wherein the central panel of the front beltportion is joined to the front waist panel of the absorbent main body,the central panel of the back belt portion is joined to the back waistpanel of the absorbent main body, and the proximal edge of therespective left and right side panels of the front belt portion and theback belt portion together with the left and right side edges of thecrotch panel of the absorbent main body defines two leg openings, eachof the leg opening has a leg opening length which can be calculatedaccording to the following formula:leg opening length=Le+Sf+√{square root over (Sb ² +La ²)} wherein Leindicates leg elastic length, Sf indicates front side panel elasticlength, Sb indicates back side panel elastic length and La indicates thedifference in the longitudinal length of the front belt portion and backbelt portion; and wherein Sb is equal to Sf.
 17. The diaper of claim 16,wherein the stretched waist circumferential length is from about 620 mmto about 700 mm.
 18. The diaper of claim 16, wherein the stretched waistcircumferential length is from about 640 mm to about 680 mm.
 19. Thediaper of claim 18, wherein the leg opening length of the diaperincludes a leg elastic length which is from about 68% to about 72% ofthe leg opening length.
 20. A disposable pull-on diaper comprising: anabsorbent main body comprising a liquid pervious topsheet, a liquidimpervious backsheet, and an absorbent core disposed therebetween,wherein the absorbent main body has left and right longitudinallyextending side edges, front and back transversely extending end edges,longitudinally opposing front and back waist panels, and a crotch panelbetween the waist panels, at least one leg elastic material disposed inproximity to each of said side edges and extending generallylongitudinally along said side edges; an elastic belt comprising a frontbelt portion and a back belt portion joined to each other at side seams,each of said front belt portion and back belt portion has transverselyextending proximal and distal edges, the distal edge of the elastic beltdefines a waist opening, the proximal edge being located closer than thedistal edge relative to the crotch panel of the absorbent main body,each of said front belt portion and back belt portion has a centralpanel; wherein the elastic belt comprises a belt substrate layer and aplurality of waist elastic strands and a plurality of side panel elasticstrands each extending in the transverse direction and attached to thebelt substrate layer; wherein said waist elastic strands are disposed inproximity to the distal edge and said side panel elastic strands aredisposed at least in the left and right side panels, and wherein theelastic belt has a stretched waist circumferential length and afree-state waist circumferential length; wherein, the central panel ofthe front belt portion is joined to the front waist panel of theabsorbent main body, the central panel of the back belt portion isjoined to the back waist panel of the absorbent main body, and theproximal edge of the respective left and right side panels of the frontbelt portion and the back belt portion together with the left and rightside edges of the crotch panel of the absorbent main body defines twoleg openings, each of the leg opening has a leg opening length which canbe calculated according to the following formula:leg opening length=Le+Sf+√{square root over (Sb ² +La ²)} wherein Leindicates leg elastic length, Sf indicates front side panel elasticlength, Sb indicates back side panel elastic length and La indicates thedifference in the longitudinal length of the front belt portion and backbelt portion; wherein, along a longitudinal axis of the disposablepull-on article, a longitudinal length of the front belt (LF) is lessthan a longitudinal length of the back belt (LB); and wherein La iszero.